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IB chemistry > D6 - D9 > Flashcards

D6 - D9 Flashcards

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1
Q

Define high-level waste

A

waste that gives off large amounts of ionising
radiation for a long time.

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2
Q

how is high-level waste produced and what does it contain?

A

Produced in nuclear reactors and contains a mixture of nuclear fission products with unused nuclear fuel

Radionuclides with long half-lives or high activity for shorter.

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3
Q

how is HLW disposed of?

A

Waste is vitrified or immobilised, then encased in steel cylinders, covered with concrete and buried deep underground in geologically stable locations.

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4
Q

Define low-level waste

A

waste that gives off small amounts of ionising
radiation for a short time.

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5
Q

explain how LLW is disposed of

A
  • has limited environmental impact and is usually suitable for shallow land burial or incineration
    Some types (i.e. large quantities/high concentrations of radionuclides) must be stored for days/weeks in shielded containers until most of the isotopes have decayed and the radiation level has dropped below a safe limit.
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6
Q

give examples of LLW

A

Radionuclides with low activity/short half life
Eg contaminated syringes, swabs, protective clothing, etc

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7
Q

describe how nuclear waste is produced

A

Many medical procedures involve the use of radionuclides (unstable isotopes that undergo spontaneous radioactive decay)
Administered as water-soluble salts/radiopharmaceutical drugs
Used in medical equipment as sources of ionising radiation
During these medical procedures radionuclides + ionising radiation come into contact with various materials, which subsequently become radioactive.
These materials, along with leftover radionuclides, produce nuclear waste.

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8
Q

what is the issue with the treatment, transportation and disposal of nuclear waste

A

present serious risks due to possible release of radionuclides to the environment.

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9
Q

what does ionising radiation cause in living organisms?

A

Cellular and genetic damage, mutations, increased probability of developing diseases such as cancer, birth defects and reproductive disorders. Also weakens the immune system.

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10
Q

environmental issues related to left-over organic solvents

A

Organic solvents used in the pharmaceutical industry constitute a significant proportion of chemical waste:
- most are toxic to living organisms, affecting
Nervous/respiratory systems, liver, kidneys, reproductive organs
- benzene (C6H6) and chloroform (CHCl3) increase risk of cancer
- many solvents are highly flammable while their vapours contribute to the greenhouse effect

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11
Q

environmental issues associate with chlorinated solvents

A
  • due to low bond enthalpy of C-Cl bonds, they act as ozone-depleting agents and contribute to the formation of photochemical smog in large cities.
  • some have low biodegradability and may accumulate in groundwater, causing damage to ecosystems
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12
Q

issues with the disposal of organic/chlorinated solvents

A
  • expensive + complex
  • cannot be incinerated with common organic waste as their incomplete combustion could produce highly toxic phosgene (COCl2) and dioxins.
  • must be oxidised separately at high temperatures/recycled by distillation.
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13
Q

Explain the dangers of antibiotic waste from hospitals and the pharmaceutical industry

A

Hospitals and the pharmaceutical industry release antibacterial waste
Exposure to low levels of antibiotics allows some bacteria to survive and mutate

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14
Q

when does antibiotic resistance occur?

A

when microorganisms become resistant to antibacterials.

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15
Q

Explain the dangers of antibiotic waste from the agricultural industry

A

They are never completely metabolised in animal organisms, so a % of each drug is excreted, therefore released into the groundwater and absorbed by other organisms. Some are also consumed by humans through animal food.

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16
Q

what is the primary goal of sustainable chemistry?

A

reduce the environmental impact of technological processes by minimising the use and generation of hazardous chemicals.

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17
Q

define atom economy

A

Expresses the efficiency of a synthetic procedure as the ratio between the molecular mass of the isolated target product and the combined molecular masses of all starting materials, catalysts and solvents used.

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18
Q

Use of biotechnologies/bioengineering in organic synthesis:

A

Enzyme catalysed reactions are highly selective, efficient and proceed in aqueous solution under mild conditions.
Drugs/synthetic intermediates can be produced from renewable materials by GMOs.

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19
Q

Explain of how green chemistry was used to develop the precursor for
Tamiflu (oseltamivir).

A

Shikimic acid is a precursor to oseltamivir (antiviral drug- Tamiflu)
For years it was extracted from Chinese star anise in a 10 stage process that took 1 year.
After the outbreak of bird flu in 2005, there was a shortage.
Shikimic acid can now be produced on an industrial scale by genetically modified E.Coli bacteria.

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20
Q

Taxol is a drug that is commonly used to

A

treat several different forms of cancer

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21
Q

Taxol occurs in … but is now …

A

yew tree; synthetically produced

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22
Q

define a chiral auxiliary

A

A chiral auxiliary is an optically active substance that is temporarily incorporated into an organic synthesis so that it can be carried out asymmetrically with the selective formation of a single enantiomer.

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23
Q

production of taxol

A

A precursor of Taxol, 10-deacetylbaccatin, is isolated from the leaves of European yew tree; the molecule of 10-deacetylbaccatin can be converted into Taxol in several synthetic steps, where the side-chain is synthesized using chiral auxiliaries and combined with 10-deacetylbaccatin.

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24
Q

why is taxol synthesised using chiral auxiliaries?

A

Because the side chains of taxol contain two chiral carbon centres their synthesis from non-chiral starting materials is problematic because it would lead to a mixture of several stereoisomers (sub-topic 20.3)
Separating the desired enantiomer from this mixture is an involved and costly process with a low yield.

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25
Q

describe and draw the process by which taxol is synthesised

A
26
Q

describe the role of the chiral auxiliary specifically in taxol synthesis

A

The role of the chiral auxiliary is to force the second intermediate to form with the desired configuration. The chiral auxiliary is then removed (and recycled) leaving the product with a single chiral centre.

27
Q

explain the use of a polarimeter to identify enantiomers

A

A polarimeter can be used to determine purity. A racemic mixture (50:50) will be optically inactive as the two opposite directions of rotation cancel each other out. A mixture consisting of two enantiomers which rotate by — and —- respectively will rotate the plane between —- and —- depending upon the ratio of the two enantiomers present.

28
Q

Alpha, beta, gamma, proton, neutron and positron emissions are used for

A

medical treatment.

29
Q

Alpha particles

A

nuclei of helium-4.

30
Q

draw symbol for alpha particles

A
31
Q

Beta particles

A

high energy electrons emitted from atomic nuclei

32
Q

draw symbol for beta particles

A
33
Q

Gamma rays

A

photons with very short wavelengths

34
Q

draw symbol for gamma rays

A
35
Q

Positrons

A

positively charged electrons

36
Q

what is Magnetic resonance imaging (MRI)

A

an application of NMR (nuclear magnetic resonance) technology

37
Q

describe MRI scanners

A

use superconductive magnets to create powerful magnetic fields and also produce radio waves.

38
Q

describes how MRI works

A
  1. When a patient is placed inside the magnet, the protons in the body constantly change their states, absorbing and emitting radio waves of a certain frequency, which are then detected by the scanner and processed on a computer.
  2. The protons in water, lipids, carbs and proteins have different chemical environments which can easily be distinguished by 1H NMR chemical shifts. The concentrations of these compounds in various tissues are different, so MRI provides detailed images.
39
Q

pros of MRI scanners

A

No ionising radiation so can be used repeatedly without increasing the risk of cancer to the patient

40
Q

cons of MRI scanners

A
  • High cost of equipment
  • Interaction of magnetic fields with metal body implants
41
Q

use of radiotherapy

A

used to treat cancer.

42
Q

two types of radiotherapy

A

internal (brachytherapy)
external

43
Q

internal radiotherapy

A

Radiation sources are inserted into the patient’s body in the form of metal wires or pellets that deliver radiation directly to the site of the disease.

44
Q

External radiotherapy

A

Involves precisely directed beams of gamma rays, protons, electrons or neutrons.

45
Q

why are cancer cells are more likely to die from radiation exposure than normal cells?

A
  • their accumulation of DNA errors, which eventually limits their ability to grow and multiply
  • their reduced ability to repair their genetic material.
46
Q

give and explain the common side effects of radiotherapy

A

Common side effects of radiotherapy: hair loss, nausea, fatigue and sterility. A long term risk of radiotherapy is the development of secondary cancers.
Normal dividing cells are also sensitive to induced DNA errors by ionising radiation.

47
Q

what are Targeted Alpha Therapy (TAT) and Boron Neutron Capture Therapy (BNCT)

A

two methods which are used in cancer treatment.

48
Q

TAT:

A
  • controlled amounts of alpha emitters can be delivered by a carrier drug or protein directly to the targeted cancer cells, which will be selectively destroyed by radiation without significant damage to the surrounding tissues.
  • at the same time, collisions of alpha and beta particles with atomic nuclei produce secondary gamma radiation, which can be detected and used to map the distribution of cancer cells in the body.
49
Q

BNCT:

A

High intensity neutron beams are used, taking advantage of the ability of boron-10 to absorb neutrons and transform into boron-11, which immediately undergoes alpha decay.
[WRITE EQUATION]
Both lithium-7 ions and alpha particles cause extensive cellular damage in a very limited range. Therefore tumours can be destroyed if they accumulate sufficient boron-10, which can be administered by intravenous injection of certain organoboron compounds.

50
Q

Explain why Technetium-99m is the most common radioisotope used in nuclear medicine based on its emission type

A

Emission type/chemistry:
- nucleus is metastable- can only exist for a short period of time
- nucleus returns to a lower energy state by emitting electromagnetic radiation:
[WRITE EQUATION]
- photons produced by t-99m have approximately the same wavelength as x-rays so can be detected using traditional x-ray material.
- energy of the photons is relatively low so reduces the radiation dose received by the patient and medical personnel.

51
Q

Explain why Technetium-99m is the most common radioisotope used in nuclear medicine based on its chemistry

A

T-99m has various oxidation states (+3, +4, +7) and readily forms complexes with various ligands, which can be administered by injection and delivered to target organs/tissues.

52
Q

Explain why Technetium-99m is the most common radioisotope used in nuclear medicine based on its half life

A

6 hours, making it ideal for medical imaging
After the gamma scan is complete nearly all the injected radionuclide decays within two days, minimising the patient’s exposure to radiation
Long enough to prepare various complexes of this radionuclide with biologically active ligands

53
Q

define half-life

A

the time required for half of the initial amount of radionuclide to decay

54
Q

two similarities between Lutetium-117 + Yttrium-90

A

Pure beta emitters used in radiotherapy
Nuclides decay in one step and produce stable isotopes:
insert equation

55
Q

Yttrium-90 is used as

A

a common radiation source for cancer brachytherapy + palliative treatment of arthritis.

56
Q

why is Lutetium-177 useful?

A
  • produces low-energy beta particles with reduced tissue penetration, which is very useful in the targeted therapy of small tumours.
  • emits just enough gamma rays for visualising tumours and monitoring the progress of their treatment.
57
Q

describe Liquid-liquid extraction and what it was used for;

A

a process that involves partitioning of a solute between two immiscible liquids.
1. A mixture of compounds is shaken with water and an organic solvent (e.g. ethoxyethane) and the resulting emulsion is allowed to settle.
2. Water and the organic solvent are almost immiscible so form two separate layers.
3. Polar compounds stay with water, non polar compounds dissolve in the organic layer.
4. Each layer is run into a different beaker using a separation funnel.
5. The organic solvent and water can be evaporated from the separate layers, leaving the components of the original mixture.

58
Q

The distribution between the two solvents is an —— process and the equilibrium constant is called the ?. For solute X dissolved in both ether and water:

A

equilibrium; partition coefficient

Ksp= [X(ether)] / [X(aq)]

59
Q

According to Raoult’s Law

A

the vapour pressure of a volatile substance A is proportional to the mole fraction of A in the mixture:
- p(A)=p*(A) x x(A)
- Ptotal= PAXA + PBXB

60
Q

describe the process of fractional distillation

A
  1. In a boiling mixture of several substances, the more volatile compounds will have higher vapour pressures and evaporate faster than other components of the mixture.
  2. Vapours of different components will partly condense and evaporate again at different heights.
  3. Each cycle of condensation and evaporation will enrich the mixture with more volatile components, increasing their mole fractions and therefore partial pressures.
  4. As a result, the vapours of more volatile components will move up the column while less volatile substances will stay as liquids and fall back into the flask.
  5. Eventually the most volatile compound will reach the top of the column, pass through the water-cooled condenser and flow into the receiver flask, producing the first fraction of the distillate.
  6. Other components in the mixture will form subsequent fractions, which can be collected in different flasks.
61
Q

describe how breathalysers work

A
  • Glass tube filled with acidified crystals of potassium dichromate (VI)- the dichromate (IV) ions are reduced by ethanol to chromium III ions, turning the orange crystals green
  • Fuel cell in which ethanol is oxidised by atmospheric oxygen on the surface of platinum electrodes; ethanol is oxidised at the anode and oxygen is reduced at the cathode. The electric current produced by the fuel cell is proportional to the concentration of ethanol in the breath.
62
Q

describe the process of steroid detection in sport

A

Athletes are regularly required to provide urine and blood samples for laboratory analyses in which steroids and their metabolites can be detected by a combination of gas chromatography (GC) or high performance liquid chromatography with mass spectrometry.

IB chemistry (29 decks)

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